Field of the Invention
The present invention relates to a liquid crystal display and a method for manufacturing the same, and more particularly, to an in-plane switching liquid crystal display and a method for manufacturing the same which can shorten takt time and increase productivity by reducing the number of masks.
Discussion of the Related Art
A liquid crystal display is generally driven using optical anisotropy and polarization properties of liquid crystals. Because the liquid crystals have an elongated shape, liquid crystal molecules have an alignment orientation. The alignment orientation of the liquid crystal molecules may be controlled by applying an electric field to the liquid crystals. Thus, when the alignment orientation of the liquid crystal molecules is adjusted, the alignment of the liquid crystal molecules may be changed. Light is refracted in the alignment orientation of the liquid crystal molecules by the optical anisotropy, thereby displaying image information.
An active matrix liquid crystal display (AMLCD) (hereinafter abbreviated to “liquid crystal display”), in which thin film transistors and pixel electrodes connected to the thin film transistors are arranged in a matrix form, has attracted much attention because of its excellent resolution and ability to display moving pictures. The liquid crystal display includes a color filter substrate on which common electrodes are typically formed, an array substrate on which the pixel electrodes are formed, and liquid crystals interposed between the color filter substrate and the array substrate. In a typical liquid crystal display, the common electrodes and the pixel electrodes drive the liquid crystals by vertically applying an electric field, which provides for good transmittance and a good aperture ratio, among other things. However, the driving of liquid crystal with the vertically applied electric field is disadvantageous in that it does not provide for good viewing angle characteristics. Thus, in order to overcome the shortcomings, an in-plane switching liquid crystal display having improved viewing angle characteristics has been proposed.
FIGS. 1A to 1F are cross-sectional views showing a related art method for manufacturing an in-plane switching liquid crystal display.
As shown in FIG. 1A, a gate pad electrode 16 and a gate electrode 18 are formed by laminating a transparent conductive layer 12 and a metal layer 14 on a substrate 10 and patterning them using a first mask. Next, as shown in FIG. 1B, a gate insulation film 20 is laminated on the substrate 10. Then, an active layer 21, a source electrode 28, a drain electrode 29, a data pad electrode 25, and a data line 27 are formed by laminating an active layer 22 and a metal layer 24 on the gate insulation film 20, and patterning them using a second mask. Next, as illustrated in FIG. 1C, a first passivation film 30 is deposited on the substrate 10 and is patterned using a third mask. Then, an organic insulation film 35 is deposited on the passivation film 30 and is patterned using a fourth mask to form a first contact hole CH1 exposing the drain electrode 28.
Next, as shown in FIG. 1D, a common electrode 45 is formed by laminating a transparent conductive material on the organic insulation film 35 and patterning it using a fifth mask to form a second contact hole CH2 exposing the drain electrode 28. Next, as shown in FIG. 1E, a second passivation film is formed on the substrate 10 and is patterned using a sixth mask to form a third contact hole CH3 exposing the drain electrode 28, a fourth contact hole CH4 exposing the gate pad electrode 16, and a fifth contact hole CH5 exposing the data pad electrode 27.
Lastly, as illustrated in FIG. 1F, a pixel electrode 60 connected to the drain electrode 28, a gate pad 65 connected to the gate pad electrode 16, and a data pad 67 connected to the data pad electrode 25 are formed by laminating a transparent conductive material on the substrate 10 and patterning it using a seventh mask.
With the use of a total of seven masks, the above-described related art method for manufacturing a liquid crystal display has a problem of low productivity because of the higher manufacturing costs and longer takt times associated with a relative high number of masks. Also, the high number of mask processes may lead to a higher percentage of manufacturing defects, thus potentially resulting in a lower yield, a higher manufacturing cost, and a decrease in the performance of the finished products.